Members Area
T: +44 (0)114 551 8170

Stainless Steel BS EN ISO 3506 Fastener Grades A1, A2, (A3), & A4 (A5)

BS EN ISO 3506 replaces BS 6105. Part 1 covers bolts, screw and studs, part 2 nuts and part 4 tapping screws. The chemical compositions are common to the various parts. Austenitic grades, A1, A2 and A4 are shown and compared to bar grades, 303, 304, 349S17, 316, and 394S17. Mechanical properties for property class, 50, 70, and 80 austenitic bolts and studs and property class, 20H, 25H, 30H, and 40H tapping screws are tabulated and the fastener designations, such as A2-70 and A4-25H described. Duplex FA, (ferritic-austenitic similar to 1.4462, (2205) of EN 10088-1) is a likely future grade for inclusion in the standard. Fastener grade selection is covered in annexes to the standards. The standards lists grades 1.4439, 1.4539, (904L), 1.4529, (6% molybdenum austenitic), and 1.4462, (2205), as suitable for reducing the risk of chloride induced stress corrosion cracking failures in applications such as indoor swimming pools.


Note a new version of BS EN ISO 3506 was issued in 2022, and as expected this now includes both duplex and higher strength grades.


Microsoft Word – SSAS2.31-Fastener Grades A1,A2_A3_ & A4_A5_ to BS EN ISO 3506 (1)

← Back to previous

↑ Top